An ion milling system is a processing system that causes bombardment of a sample by accelerated ions and that cuts the sample using sputtering that the ions dislodge atoms and molecules. Furthermore, a mask that serves as an ion beam masking shield is placed on an upper surface of the sample to be processed, and a protruding portion of the sample from a mask end surface (exposed portion thereof that is not covered with the mask) is sputtered, whereby the sample can be processed to have a smooth cross-section. The ion milling system is employed for a target such as metal, glass, ceramics, an electronic component, or a composite material. For example, if the electronic component is a target, the ion milling system is used to create a cross-section sample for acquisition of a morphological image, a sample composition image, and a channeling image by a scanning electron microscope or for acquisition by X-ray analysis, crystal orientation analysis, or the like for use applications including evaluation of an internal structure, a cross-sectional area shape, and a film thickness and analysis of a crystalline state, a failure, and a foreign substance cross-section.
Demand is high for combination of the ion milling system with an electron microscope system for the purpose of improving usability, responding to demand of three-dimensional analysis, responding to demand of analysis of a material that cannot be exposed to the atmosphere, or the like. Patent Document 1 discloses an ion milling system in which an electron microscope is mounted as a technique for checking a progress of milling processing while a sample is being subjected to the milling processing by an ion beam. Patent Document 2 discloses a method of observing an internal structure of a sample by a scanning electron microscope while the sample is gradually subjected to ion milling processing starting with a surface of the sample, as a method of three-dimensionally analyzing the internal structure of the sample. Patent Document 3 discloses a method with using a scanning electron microscope provided with a sample preprocessing system in which anion gun is mounted, the method sequentially observing a structure of a sample in a depth direction from a surface of the sample by a scanning electron microscope while the sample is gradually subjected to ion polishing starting with the surface of the sample in the same vacuum as that in which the structure is observed.